1. Field of the Invention
This invention relates to computer systems and, more particularly, to input/output (I/O) devices with shared I/O resources.
2. Description of the Related Art
There have been significant increases in the effective throughput of a variety of I/O devices used in computing systems. In the recent past, a number of new communication standards have been introduced. For example, 10 Gigabit Ethernet may allow up to ten gigabits of information to be conveyed and Peripheral Component Interconnect Express (PCIe™) Generation 1 may allow up to 2.5 Gbits per lane. In many computer systems, a single processor, processing module, or device typically does not use that much I/O bandwidth. Accordingly, in an effort to increase hardware resource utilization, sharing of the I/O hardware resources across multiple processing modules may be desirable.
One mechanism for sharing resources that use PCIe interfaces is to virtualize the resources across multiple processing elements. Thus, I/O virtualization standards have been introduced, such as for example, the single root and multi-root PCIe specifications. However, there are issues with virtualizing and sharing of some hardware resources. For example, an I/O device that implements a PCIe interface uses the notion of a function. Functions may be used to access respective hardware resources. However, for a variety of reasons, a function and its resources may need to be reset or reclaimed by the supervisory system software without perturbing the operation of any other function or process.